U.S. patent application number 13/796872 was filed with the patent office on 2014-09-18 for pneumatic sheet registration and clamping with vectored air flow.
This patent application is currently assigned to XEROX CORPORATION. The applicant listed for this patent is XEROX CORPORATION. Invention is credited to Douglas K. Herrmann, James Joseph Spence.
Application Number | 20140267523 13/796872 |
Document ID | / |
Family ID | 51419213 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140267523 |
Kind Code |
A1 |
Herrmann; Douglas K. ; et
al. |
September 18, 2014 |
PNEUMATIC SHEET REGISTRATION AND CLAMPING WITH VECTORED AIR
FLOW
Abstract
A pneumatic table for registering and clamping thereon a sheet
of substrate media for handling in a printing system. The pneumatic
table includes a media platen having a foraminous upper surface for
receiving a substrate media sheet. A first reversible air blower is
in fluid communication with the media platen and selectively
generates at least one of a positive air flow and a negative
airflow through the foraminous upper surface. The positive air flow
forms a gaseous layer of air between the foraminous upper surface
and the substrate media sheet. The negative airflow encourages the
substrate media sheet to remain fixed and engaged upon the
foraminous upper surface. A registration wall extends along at
least one edge of the foraminous upper surface. A sheet biasing
element includes a directionally vectored positive air flow. The
sheet biasing device selectively applies a biasing force to the
substrate media sheet encouraging movement of the substrate media
sheet across the foraminous upper surface for engaging the
substrate media sheet with the registration wall.
Inventors: |
Herrmann; Douglas K.;
(Webster, NY) ; Spence; James Joseph; (Honeoye
Falls, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XEROX CORPORATION |
Norwalk |
CT |
US |
|
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
51419213 |
Appl. No.: |
13/796872 |
Filed: |
March 12, 2013 |
Current U.S.
Class: |
347/104 |
Current CPC
Class: |
B41J 11/0085 20130101;
B41J 11/06 20130101; B41J 13/26 20130101 |
Class at
Publication: |
347/104 |
International
Class: |
B41J 13/26 20060101
B41J013/26 |
Claims
1. A pneumatic table for registering and clamping thereon a sheet
of substrate media for handling in a printing system, the pneumatic
table comprising: a media platen, the media platen having a
foraminous upper surface for receiving a substrate media sheet; a
first reversible air blower being in fluid communication with the
media platen, the first reversible air blower selectively
generating at least one of a positive air flow and a negative
airflow through the foraminous upper surface, wherein the positive
air flow forming a gaseous layer of air between the foraminous
upper surface and the substrate media sheet, the negative airflow
encouraging the substrate media sheet to remain fixed and engaged
upon the foraminous upper surface; a registration wall extending
along at least one edge of the foraminous upper surface; and a
sheet biasing element including a directionally vectored positive
air flow, the sheet biasing device selectively applying a biasing
force to the substrate media sheet encouraging movement of the
substrate media sheet across the foraminous upper surface for
engaging the substrate media sheet with the registration wall.
2. The pneumatic table as defined in claim 1, wherein the first
reversible air blower is configured to provide a virtually
instantaneous transition from positive air flow to negative air
flow.
3. The pneumatic table as defined in claim 1, further comprising:
an edge sensor for detecting a position of the substrate media
sheet, the edge sensor disposed along a portion of the registration
wall for detecting the substrate media sheet has attained a target
registration position.
4. The pneumatic table as defined in claim 1, wherein the
registration wall extends along two adjoining edges of the
foraminous upper surface.
5. The pneumatic table as defined in claim 1, wherein the
registration wall extends continuously along the at least one edge
substantially as long as at least one edge of the substrate media
sheet.
6. The pneumatic table as defined in claim 1, wherein the biasing
element includes a first set of angled holes extending through the
media platen, the first set of angled holes providing the
directionally vectored positive air flow, the first set of angled
holes being in fluid communication with the first reversible air
blower.
7. The pneumatic table as defined in claim 7, wherein the media
platen includes a second set of air holes each having a generally
an orientation for directing an air flow substantially
perpendicular to the platen surface, the second set of air holes
being in fluid communication with a second reversible air first
blower.
8. The pneumatic table as defined in claim 7, wherein the holes of
the first set of holes are each aligned to direct air flow toward
the registration wall.
9. The pneumatic table as defined in claim 8, wherein the second
set of holes are disposed adjacent to the registration wall.
10. The pneumatic table as defined in claim 8, wherein the first
set of holes and the second set of holes are interlaced with each
other over a substantial portion of the media platen.
11. The pneumatic table as defined in claim 7, wherein a positive
air flow is provided to the first set of air holes and
simultaneously a negative air flow is provided to the second set of
air holes.
12. The pneumatic table as defined in claim 1, wherein the first
and second set of holes have a diameter in the range of 0.5 mm to 4
mm and a hole density generally in the range of 1 to 10 per
cm.sup.2.
13. A method of registering and securing a sheet of substrate media
on a media platen for handling in a printing system, the method
comprising: loading a substrate media sheet onto a media platen,
the media platen including a foraminous upper surface for engaging
the substrate media sheet; generating a positive flow of air
through the foraminous upper surface, the positive flow of air
forming a gaseous layer of air between the foraminous upper surface
and the substrate media sheet; applying a generally biasing force
to the substrate media sheet at least partially suspended on the
gaseous layer, the biasing force including a directionally vectored
positive air flow passing through the media platen; and generating
a negative flow of air through the foraminous upper surface, the
negative flow of air encouraging the substrate media sheet to
remain fixed and engaged upon the foraminous upper surface.
14. The method as defined in claim 13, wherein the media platen
includes a first set of angled holes extending through the media
platen, the first set of angled holes providing the directionally
vectored positive air flow.
15. The method as defined in claim 14, wherein the media platen
includes a second set of holes having a generally vertical
orientation for directing an air flow substantially perpendicular
to the platen surface.
16. The method as defined in claim 15, wherein in response to the
sheet reaching a predetermined position, applying a negative
pressure to the second set of holes to develop the negative flow of
air to draw a portion of the sheet to the platen.
17. The method as defined in claim 16, applying a negative pressure
to the first set of holes to draw a remainder of the sheet to the
platen after.
18. The method as defined in claim 12, wherein the second set of
holes are located on a portion of the platen separate and distinct
from the first set of holes.
19. The method as defined in claim 12, wherein the second set of
holes are interlaced with the first set of holes.
20. The method as defined in claim 12, wherein the negative flow of
air is generated in response to an indication by a sensor that the
substrate media sheet has engaged a registration wall extending
along at least one edge of the foraminous upper surface.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to an apparatus for and
method of registering and clamping sheets of substrate media
transported on a moveable platen in a printing system.
BACKGROUND
[0002] High speed inkjet marking devices for large sized cut sheets
are particularly constrained using contemporary systems with regard
to production output, media type and image quality. Systems that
handle such large sized cut sheets can use an oversized media
platen to support the sheet during the marking process, but
placement and registration of the sheet on the platen requires
precision. Also, once the sheet is moved into the desired
registration position, that position must be reliability
maintained. However, such large sheets are particularly difficult
to manipulate into and maintain in proper registration upon the
platen, particularly if it is a moveable platen.
[0003] Accordingly, it would be desirable to provide an apparatus
for and method of registering and clamping a sheet of substrate
media on a media platen for handling in a printing system that
overcomes the various shortcomings of the prior art.
SUMMARY
[0004] According to aspects described herein, there is disclosed a
pneumatic table for registering and clamping thereon a sheet of
substrate media for handling in a printing system. The pneumatic
table includes a media platen having a foraminous upper surface for
receiving a substrate media sheet. A first reversible air blower is
in fluid communication with the media platen and selectively
generates at least one of a positive air flow and a negative
airflow through the foraminous upper surface. The positive air flow
forms a gaseous layer of air between the foraminous upper surface
and the substrate media sheet. The negative airflow encourages the
substrate media sheet to remain fixed and engaged upon the
foraminous upper surface. A registration wall extends along at
least one edge of the foraminous upper surface. A sheet biasing
element includes a directionally vectored positive air flow. The
sheet biasing device selectively applies a biasing force to the
substrate media sheet encouraging movement of the substrate media
sheet across the foraminous upper surface for engaging the
substrate media sheet with the registration wall.
[0005] Additionally, the reversible air blower can be configured to
provide a virtually instantaneous transition from positive air flow
to negative air flow. Alternatively, the reversible air blower can
be configured to provide a progressive transition across the
foraminous upper surface from positive air flow to negative air
flow. The pneumatic table can further include an edge sensor for
detecting a position of the substrate media sheet. The edge sensor
disposed along a portion of the registration wall for detecting the
substrate media sheet has attained a target registration position.
The registration wall can extend along two adjoining edges of the
foraminous upper surface. The registration wall can also extend
continuously along the at least one edge substantially as long as
at least one edge of the substrate media sheet. At least a portion
of the registration wall can be selectively moveable in order to
allow the substrate media sheet to slide off the foraminous upper
surface.
[0006] According to further aspects described herein, there is
disclosed a method of registering and securing a sheet of substrate
media on a media platen for handling in a printing system, the
method including loading a substrate media sheet onto a media
platen, the media platen including a foraminous upper surface for
engaging the substrate media sheet; generating a positive flow of
air through the foraminous upper surface, the positive flow of air
forming a gaseous layer of air between the foraminous upper surface
and the substrate media sheet; applying a generally biasing force
to the substrate media sheet at least partially suspended on the
gaseous layer, the biasing force including a directionally vectored
positive air flow passing through the media platen; and generating
a negative flow of air through the foraminous upper surface, the
negative flow of air encouraging the substrate media sheet to
remain fixed and engaged upon the foraminous upper surface.
[0007] Additionally, the negative flow of air can be generated in
response to the positive flow of air no longer passing through at
least a portion of the foraminous upper surface that previously had
the positive flow of air passing therethrough. Also, a virtually
instantaneous transition can be provided from the generation of the
positive flow of air to the generation of the negative flow of air.
A progressive transition across the foraminous upper surface can
alternatively be provided from the generation of the positive flow
of air to the generation of the negative flow of air. The negative
flow of air can be generated in response to an indication by a
sensor that the substrate media sheet has engaged a registration
wall extending along at least one edge of the foraminous upper
surface. The registration wall engagement can include the substrate
media engaging two extents of the registration wall. The two
extents of the registration wall can be disposed along two
adjoining edges of the foraminous upper surface.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a plan view of a pneumatic table for registering
and transporting a skewed sheet of substrate media being biased
toward a registration corner in accordance with an aspect of the
disclosed technologies.
[0009] FIG. 2 is a plan view of the pneumatic table shown in FIG. 1
with a de-skewed sheet of substrate media biased into a registered
orientation in accordance with an aspect of the disclosed
technologies.
[0010] FIG. 3 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 1 with positive airflow through the
table in accordance with an aspect of the disclosed
technologies.
[0011] FIG. 4 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 2 with positive airflow through a
table media platen in accordance with an aspect of the disclosed
technologies.
[0012] FIG. 5 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 2 with a first set of holes having a
positive airflow through the table and a second set of holes having
a negative airflow through the table media platen in accordance
with an aspect of the disclosed technologies.
[0013] FIG. 6 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 2 with negative airflow through the
entire table media platen in accordance with an aspect of the
disclosed technologies.
[0014] FIG. 7 is a partial plan view of a portion of the upper
surface of an alternative embodiment of a pneumatic table in
accordance with an aspect of the disclosed technologies.
[0015] FIG. 8 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 7 with positive airflow through the
table media platen in accordance with an aspect of the disclosed
technologies.
[0016] FIG. 9 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 7 with positive airflow through the
table media platen in accordance with an aspect of the disclosed
technologies.
[0017] FIG. 10 is a side cross-sectional elevation view of the
pneumatic table shown in FIG. 7 with negative airflow through the
entire table media platen in accordance with an aspect of the
disclosed technologies.
DETAILED DESCRIPTION
[0018] Describing now in further detail these exemplary embodiments
with reference to the Figures. The disclosed technologies improve
image quality for large format print jobs, while providing an
efficient sheet registration and handling system that can improve
productivity. The apparatus and methods disclosed herein can be
used in a select location or multiple locations of a marking device
path that includes a pneumatic table. Thus, only a portion of an
exemplary pneumatic table and methods of use thereof are
illustrated herein.
[0019] As used herein, "substrate media sheet", "substrate media"
or "sheet" refers to a substrate onto which an image can be
imparted. Such substrates may include, paper, transparencies,
parchment, film, fabric, plastic, photo-finishing papers,
corrugated board, or other coated or non-coated substrate media
upon which information or markings can be visualized and/or
reproduced. While specific reference herein is made to a sheet or
paper, it should be understood that any substrate media in the form
of a sheet amounts to a reasonable equivalent thereto. Also, the
"leading edge" of a substrate media refers to an edge of the sheet
that is furthest downstream in a process direction.
[0020] As used herein, "sensor" refers to a device that responds to
a physical stimulus and transmits a resulting impulse in the form
of a signal for the measurement and/or operation of controls. Such
sensors include those that use pressure, light, motion, heat, sound
and magnetism. Also, each of such sensors as refers to herein can
include one or more sensors for detecting and/or measuring
characteristics of a substrate media, such as speed, orientation,
process or cross-process position and even the size of the
substrate media. Thus, reference herein to a "sensor" can include
more than one sensor.
[0021] As used herein, "marking zone" refers to the location in a
substrate media processing path in which the substrate media is
altered by a "marking device." Marking devices as used herein
include a printer, a printing assembly or printing system. Such
marking devices can use digital copying, bookmaking, folding,
stamping, facsimile, multi-function machine, and similar
technologies. Particularly those that perform a print outputting
function for any purpose.
[0022] Particular marking devices include printers, printing
assemblies or printing systems, which can use an
"electrostatographic process" to generate printouts, which refers
to forming an image on a substrate by using electrostatic charged
patterns to record and reproduce information, a "xerographic
process", which refers to the use of a resinous powder on an
electrically charged plate record and reproduce information, or
other suitable processes for generating printouts, such as an ink
jet process, a liquid ink process, a solid ink process, and the
like. Also, a printing system can print and/or handle either
monochrome or color image data.
[0023] As used herein, the term "foraminous surface" refers to a
surface having a plurality or holes therein. The surface may be
perforated, porous, or otherwise include numerous holes. The holes
may allow the passage of air there through.
[0024] As used herein, the terms "process" and "process direction"
refer to a process of moving, transporting and/or handling a
substrate media sheet. The process direction substantially
coincides with a direction of a flow path P along which a portion
of the media sled moves and/or which the image or substrate media
is primarily moved within the media handling assembly. Such a flow
path P is said to flow from upstream to downstream. Accordingly,
cross-process, lateral and transverse directions refers to
movements or directions perpendicular to the process direction and
generally along a common planar extent thereof.
[0025] FIG. 1 shows a plan view of a pneumatic table 10 for
registering and clamping a sheet of substrate media 5 placed
thereon. When printing a sheet, such as a sheet of paper, on a
media platen, precise registration of the sheet must be
accomplished before the sheet can be marked or further processed.
The media platen generally formed as a flat rigid plate for
supporting the substrate media sheet. Generally the media platen
can be a flat metal surface which will support the sheet when
pressure is applied thereto, particularly as part of a printing
process using marking devices.
[0026] With additional reference to FIG. 2, the sheet 5 when placed
on the platen 100 may be skewed and/or improperly positioned on the
platen 100. Thus, according to an aspect of the disclosed
technologies, it is desirable to have the sheet 5 properly
registered relative to a process direction P as well as a
cross-process direction C.sub.P. A preferred registration position
for the leading edge L.sub.E of the sheet 5 is when it is precisely
aligned with the downstream edge of the media platen 100. That edge
of the media platen 100 coincides with a side of a leading edge
registration wall 130. Thus, by bringing the leading edge L.sub.E
of the sheet 5 into engagement with the leading edge registration
wall 130 the first part of the target registration position is
achieved. Similarly, a preferred registration position for the left
side lateral edge of the sheet 5 (the bottom edge as shown in the
drawings) is when that sheet edge is aligned with the outboard edge
of the media platen 100 (also the bottom edge as shown in the
drawings). Thus, by also bringing the left lateral sheet edge into
engagement with a lateral edge registration wall 140 the second
part of the target registration position is achieved. The order, if
any, in which these parts of the position are achieved is a matter
of design choice and depends on how the sheet is moved into the
target registration position. The registration walls 130 and 140
each extend above the upper surface 102 and provide an abutment
surface for assisting in aligning the sheet in the registration
position. At least a portion of the registration walls may be
selectively moveable in order to allow the substrate media sheet to
slide off the foraminous upper surface.
[0027] In accordance with a further aspect of the disclosed
technologies, the pneumatic table 10 includes a media platen 100
that has a foraminous upper surface 102. The pneumatic table 10
operates by means of air, particularly compressed air, that can be
expelled through the foraminous upper surface 102 or the flow
reversed to create a vacuum force on the foraminous upper surface
102. The foraminous upper surface can be porous, perforated or
otherwise include numerous holes so that air can be expelled from
the foraminous upper surface 102 of the media platen 100. In the
illustrated embodiment, the foraminous upper surface 102 includes a
plurality of air holes 120 that are evenly distributed in columns
and rows across the top surface of the media platen 100. It should
be understood that other configurations of air holes 120 could be
provided, so that fewer or greater numbers of such holes can form
the foraminous upper surface. Additionally, other patterns could be
formed, such as concentric arches emanating from the corner between
the two registration walls 130, 140. Also, the air holes 120 need
not be evenly space across the entire surface. As an alternative to
the air holes 120, the foraminous upper surface 102 could be a
generally porous surface with less discrete apertures. Regardless,
the discrete air holes 120 or less than discrete apertures forming
a porous surface are preferably in fluid communication with at
least one reversible air blower that provides a source of
selectively positive and/or negative air flow for the pneumatic
table 10.
[0028] The air holes may have a diameter within the range of 0.5 mm
to 4 mm. The surface may have air hole density of approximately 1
to 10 per square centimeter, cm.sup.2. It is contemplated that the
hole size and density may be varied. It is further contemplated
that various hole sizes could be used on a surface and that the
density of holes could vary over the surface depending on the
desired air flow.
[0029] The air holes 120 may include a first set of air holes 150
and a second set of air holes 152. The first set of air holes may
be angled such that the air flowing therefrom is vectored (shown by
arrows 154) toward a registration corner 156. The positive air flow
therefore creates a biasing force to drive the sheet against the
registration walls. The first set of air holes 150 is disposed
about a substantial portion of the platen. The second set of holes
may include straight holes aligned substantially perpendicular to
the platen upper surface 102. The second set of holes 152 may be
disposed on the platen along the registration wall adjacent the
leading edge of the sheet.
[0030] With reference to FIG. 3, the first set of holes 150 may be
connected to a first reversible air blower 180 that is capable of
developing both a positive air flow and a negative air flow. The
second set of holes 152 may be connected to a second reversible air
blower 182 that is capable of developing both a positive air flow
and a negative air flow. This permits the air flow to the first and
second holes to be independently controlled. Accordingly, positive
pressure may be simultaneously applied to the first set of holes
and negative pressure applied to the second set of holes and vice
versa.
[0031] FIGS. 3-6 show a side cross-sectional elevation view of the
pneumatic table shown in FIGS. 1-2. These side views include a
schematic representation of the first and second reversible air
blowers 180 and 182, which represent any device capable of
producing a current of air or gas, selectively in at least two
directions. Provided appropriate tubing channels or conduits (not
shown) between the air holes 120 and the first and second
reversible air blowers 180 and 182 will place the air holes 120 in
fluid communication with the reversible air blower 180. In this
way, any air blowing from the reversible air blower will exit the
air holes in the foraminous upper surface 102 or vacuum force
generated will communicate a suction force on that upper surface
102.
[0032] Once a sheet 5 is placed on the pneumatic table 10, positive
air flow emitted from the foraminous upper surface 102 will cause
the sheet 5 to float on a gaseous layer of air formed between the
upper surface 102 and the sheet 5. It should be understood that the
positive air flow can be emitted before, during or after the sheet
5 is placed on the pneumatic table 10. The gaseous layer of air
reduces friction or electrostatic forces that might otherwise hold
the sheet 5 in a skewed or otherwise disoriented position on the
platen.
[0033] In accordance with an aspect of the disclosed technologies,
when the sheet 5 is floating due to the positive airflow, the
vectored air flow exiting the first set of air holes 150 forms a
horizontal biasing force B.sub.1 that is applied to the floating
sheet 5. The horizontal biasing force B.sub.1 encourages the sheet
5 to move towards both upwardly standing registration walls 130,
140. Once the sheet 5 is engaged against both the leading edge
registration wall 130 and the lateral edge registration wall 140,
it will have attained the target registration position, as shown in
FIG. 2. The registration walls 130, 140 can extend across an entire
extent of each of the respective platen edges, such as the lateral
wall 140 or extend across a more limited extent, such as the lead
edge wall 130. Also the walls 130, 140 can be continuous solid
walls or include apertures for allowing extraneous air flow to pass
therethrough.
[0034] The horizontal biasing force B.sub.1 will understandably
have a mean directional vector. In this regard, while the direction
of this initial force B.sub.1 should generally be toward the corner
156 adjoining the two registration walls 130, 140, the amount of
force can vary depending on factors such as the size and weight of
the substrate media sheet 5.
[0035] The pneumatic table and methods described herein are
particularly useful for handling large size substrate media sheets.
In particular, large size paper having dimensions of
62''.times.42'' can be easily accommodated by the disclosed
technologies. What is more, larger sheets can be handled as long as
the media platen 100 is sized accordingly.
[0036] Additionally, it should be understood that the pneumatic
table 10 disclosed herein can be operated in conjunction with a
controller 190. The controller 190 may be operably connected to the
first and second reversible air blowers 180 and 182 to direct the
operation and direction of air flow. The controller may also
control any number of functions and systems within or associated
with the pneumatic table 10 and accompanying marking systems. The
controller 190 may include one or more processors and software
capable of generating control signals. Through the coordinated
control of the apparatus sub-elements, including the first and
second reversible air blowers 180 and 182, vectored air flow and
media position detection sensors 200, the substrate media sheet may
be effectively handled and marked. Further, it should be understood
that the controller can also operate related items such as a sheet
loader for initially placing the substrate media sheet onto the
pneumatic table 10. Such a sheet loader can take the form of a
6-axis adept robot system for picking and placing sheets, such as
large sheets of substrate media, on the media platen 100.
[0037] The biasing force directs the sheet to the registration
position. Sensors 200 may be disposed on or adjacent to the
registration walls 130, 140 to detect when the sheet 5 has reached
the target registration position. The sensors 200 may be operably
connected to the controller 190.
[0038] Once the sheet 5 reaches the target registration position as
shown in FIGS. 2 and 4, the sensors 200 signal the controller 190.
With reference to FIG. 5, the controller 190 causes the second
reversible air blower 182 operably connected to the second set of
air holes 152 to switch from generating positive air flow to
generating a vacuum force (also referred to herein as a negative
air flow). Such negative air flow provides a suction force
encouraging the portion of the substrate media sheet 5 above the
second set of air holes 152 to be pulled straight down to
foraminous upper surface 102 and is tacked in place. This is done
with the vectored positive air flow still urging the sheet into the
target registration position. Tacking a portion of the sheet down
tends to hold the sheet in place and eliminates sheet drift. Once
the edge of the sheet is tacked down, the first reversible air
blower 180 operably connected to the first air holes 150 then will
switch from generating positive air flow to generating a vacuum
force. This vacuum clamps the entire sheet to the platen surface,
and the sheet is securely held in place in a correctly registered
position.
[0039] In and alternative embodiment shown in FIGS. 7-10, the first
set of holes 150 and second set of holes 152 may be disposed in
interlaced rows 210 with each other over the entire surface of the
media platen 102. In order to urge the sheet to the registration
position, the first set of holes 150 which are angled with respect
to the platen surface 102 is filled with positive pressure. This
creates a vectored airflow to float the sheet 5 into the
registration position. When the sensors 200 determine that the
sheet is in the registration position, the controller 190 causes
the second blower 182 to generate a negative pressure through the
second set of holes 152. The second set of holes 152 are aligned
substantially perpendicular with respect to the platen surface 102
and are generally vertical. The positive pressure to the first set
of holes 150 it turned off. The sheet 5 is then pulled down to the
platen surface 102 and held in place at the registration
position.
[0040] According to one aspect of the disclosed technologies, the
switch between positive air flow and negative air flow can be a
virtually instantaneous transition. Nonetheless, it is desirable
that the transition be as quick as possible so that the substrate
media sheet 5 stays in the target registration position and remains
there when the negative air flow is applied. As a further
alternative, the transition between positive and negative air flow
can be provided progressively across the foraminous upper surface.
In this way, some of the vectored first air holes 150 may be
applying positive air flow to hold the sheet 5 in the registration
position, when some of the straight vertical second air holes 152
are subject to negative air flow to tack the sheet down. After a
portion of the sheet is tacked down, the positive pressure to the
first set of air holes 150 is terminated and all of the second set
of air holes 152 may be subjected to a negative pressure. This will
cause the entire sheet to be pulled straight down to the platen
surface 102 and held in the registration position.
[0041] With reference to FIGS. 1, 3 and 4, in operation, a sheet 5
is placed on the media platen 100. The sheet is initially not in
the registration position. A positive air flow 220 is shown
emitting from the upper surface 102 though both the first and
second set of air holes. A gap Z between the sheet 5 and the upper
surface 102 is filled with a gaseous layer causing the sheet 5 to
float above the upper surface. The vectored air flow moves the
sheet toward the registration position as shown in FIG. 4
[0042] With reference to FIG. 5, when the sensors 200 detect the
sheet is in registration position, the controller 190 causes the
second blower to reverse and to start generating a negative airflow
222. This causes an edge of the sheet 5 to be pulled toward the
surface and held in place. After a predetermined time, the
controller 190 causes the first blower 180 to revise and generate a
negative airflow 222 in the first set of holes 150. Therefore, a
negative airflow is generated over the entire platen upper surface
102. This results in the remainder of the sheet being secured to
the platen's surface 102 by vacuum as shown in FIG. 6. Once the
sheet 5 is vacuum clamped in the target registration position, it
is ready for marking or further processing by a printing
system.
[0043] For the operation of the embodiment shown in FIGS. 7-10, a
positive air flow 220 is shown emitting from the upper surface 102
though the first set of air holes 150. A gap Z between the sheet 5
and the upper surface 102 is filled with a gaseous layer causing
the sheet 5 to float above the upper surface. The vectored air flow
moves the sheet toward the registration position, FIG. 9.
[0044] With reference to FIG. 10, when the sensors 200 detect the
sheet is in registration position, the controller 190 causes the
second blower to reverse and to start generating a negative airflow
222. This causes the sheet 5 to be pulled toward the surface 102.
This occurs while positive air is being applied to the first set of
air holes 150. After a predetermined time, the controller 190
causes the first blower to revise and generate a negative pressure.
This results in the first set of air holes 150 generating a
negative air pressure and the sheet is secured to the platen by
vacuum as shown in FIG. 6. Once the sheet 5 is vacuum clamped in
the target registration position, it is ready for marking or
further processing by a printing system.
[0045] Further, the pneumatic table 10 can be carried by a media
sled to a marking zone. In this way, a printing system, such as an
inkjet assembly can mark the substrate sheet 5 as it passes.
Alternatively and/or additionally, a variety of devices for
generating an image could be used. For example, xerographic,
flexographic or lithographic image transfer systems could be
employed.
[0046] It will be appreciated that variations of the
above-disclosed and other features and functions, or alternative
thereof, may be desirably combined into many other different
systems or applications. Various presently unforeseen or
unanticipated alternatives, modifications, variations, or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims. In addition, the claims can encompass embodiments in
hardware, software, or a combination thereof.
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